The drive rods of progressive cavity pumps, also known as screw-type pumps, tend to impart torque to the pump during operation. This torque causes both the pump and the tubing string to rotate in a right hand direction, when viewed from the top. Such rotation is detrimental to the pumping operation.
An anchor is known for use with a progressive cavity pump and is described in U.S. Pat. No. 4,811,785 issued Mar. 14, 1989 to Weber. This anchor has a drag assembly and a slip assembly disposed about a central tubular member though which the well fluids can pass. The drag assembly carries a drag means, such as spring-biased drag blocks or belly-type springs, and is free to rotate relative to the tubular member. The slip assembly is formed about the tubular member in engagement with the drag assembly. The slip assembly houses slip members having casing engaging surfaces, which are driven between a retracted position and an extended engaging position by action of the drag and slip assemblies rotating about the central tubular member and slip members moving over the surface of the tubular member where it is formed as a mandrel.
This anchor, and particularly the slip housing and slip members of the anchor, are quite complex and difficult to assemble. This factor makes initial manufacture, refurbishment and repair expensive and undesirable. In addition, the slips are mounted in the slip housing in such a way that causes premature wear and failure of the anchor.